Update test to include non-uniform case

pytorch3d/structures/meshes.py

@@ -1559,20 +1559,24 @@ def volume_centroid(self):
         """
         v_idxs = self.faces_padded().split([1, 1, 1], dim=-1)
         verts = self.verts_padded()
-
-        v0, v1, v2 = [torch.gather(verts, 1, idx.expand(-1, -1, 3)) for idx in v_idxs]
+        valid = (self.faces_padded() != -1).all(dim=-1, keepdim=True)
+
+        v0, v1, v2 = [
+            torch.gather(
+                verts,
+                1,
+                idx.where(valid, torch.zeros_like(idx)).expand(-1, -1, 3),
+            ).where(valid, torch.zeros_like(idx, dtype=verts.dtype))
+            for idx in v_idxs
+        ]
 
         tetra_center = (v0 + v1 + v2) / 4
         signed_tetra_vol = (v0 * torch.cross(v1, v2, dim=-1)).sum(
             dim=-1, keepdim=True
         ) / 6
         denom = signed_tetra_vol.sum(dim=-2)
         # clamp the denominator to prevent instability for degenerate meshes.
-        denom = torch.where(
-          denom < 0,
-          denom.clamp(max=-1e-5),
-          denom.clamp(min=1e-5)
-        )
+        denom = torch.where(denom < 0, denom.clamp(max=-1e-5), denom.clamp(min=1e-5))
         return (tetra_center * signed_tetra_vol).sum(dim=-2) / denom
 
     def submeshes(

tests/test_meshes.py

@@ -1299,13 +1299,24 @@ def test_assigned_normals(self):
             self.assertFalse(torch.allclose(yes_normals.verts_normals_padded(), verts))
 
     def test_centroid(self):
+        meshes = init_simple_mesh()
+        # Check that it returns a valid value for multiple meshes with an inconsistent number
+        # of vertices
+        meshes.volume_centroid()
+
         cube = init_cube_meshes()
-        self.assertClose(cube.volume_centroid(), torch.tensor([
-          [0.5] * 3,
-          [1.5] * 3,
-          [2.5] * 3,
-          [3.5] * 3,
-        ]))
+        self.assertClose(
+            cube.volume_centroid(),
+            torch.tensor(
+                [
+                    [0.5] * 3,
+                    [1.5] * 3,
+                    [2.5] * 3,
+                    [3.5] * 3,
+                ]
+            ),
+        )
+
     def test_submeshes(self):
         empty_mesh = Meshes([], [])
         # Four cubes with offsets [0, 1, 2, 3].